Ado-Trastuzumab Emtansine in Treating Patients With HER2-Positive Metastatic or Locally Advanced Breast Cancer That Cannot Be Removed by Surgery

This phase I trial studies the side effects and best way of giving ado-trastuzumab emtansine in treating patients with human epidermal growth factor receptor 2 (HER2)-positive metastatic or locally advanced breast cancer that cannot be removed by surgery. Biological therapies, such as ado-trastuzumab emtansine may stimulate the immune system in different ways and stop cancer cells from growing.

Eligibility Criteria (must meet the following to participate in this
study)

- For women of childbearing potential and men with partners of childbearing potential, agreement by the patient and/or partner to use a highly effective, non-hormonal form of contraception or two effective forms of non-hormonal contraception

Exclusions (conditions that would prevent participation in this
study)

- Known platelet disorder, such as von Willebrand's disease or baseline platelet count of < 100,000/mm^3

- Chemotherapy =< 21 days before first study treatment

- Trastuzumab =< 21 days before first study treatment

- Lapatinib =< 14 days before first study treatment

- Investigational therapy or any other therapy =< 28 days before first study treatment

- Any prior ado-trastuzumab emtansine

- Previous radiotherapy for the treatment of unresectable, locally advanced/recurrent or metastatic breast cancer is not allowed if:

- * The last fraction of radiotherapy has been administered within 14 days prior to randomization

- * The patient has not recovered from any resulting acute toxicity (to grade =< 1) prior to randomization

- Brain metastases that are untreated or symptomatic, or require any radiation, surgery, or steroid therapy to control symptoms from brain metastases within 30 days of first on-study thrombokinetic study; for patients with newly diagnosed brain metastases or unequivocal progression of brain metastases on screening scans, localized treatment (i.e., surgery, radiosurgery, and/or whole brain radiotherapy) is required before study enrollment; subjects with known brain metastases must have clinically controlled neurologic symptoms, defined as surgical excision and/or radiation therapy followed by 14 days of stable neurologic function prior to the first thrombokinetic procedure; patients with small brain metastases not symptomatic and deemed requiring treatment by managing clinicians or study investigators may be permitted to enroll on study

- History of intolerance (including grade 3 or 4 infusion reaction) or hypersensitivity to trastuzumab or murine proteins

- Current peripheral neuropathy of grade >= 3 per the National Cancer Institute Common Terminology Criteria for Adverse Events (NCI CTCAE) v. 4.0